How Can This Be?

In Mark 4:11-15: "As soon as He was alone, His followers, with the twelve, began asking Him about the parables. And He was saying to them, ''To you has been given the mystery of the kingdom of God, but those who are outside get everything in parables, so that while seeing, they may see and not perceive, and while hearing, they may hear and not understand; otherwise they might return and be forgiven.'' And He said to them, ''Do you not understand this parable?